type Props = {
  className: string
  children: React.ReactNode
}

function Button(props: Props) {
  const { className, children } = props
  return <button className={className}>{children}</button>
}

function App() {
  return (
    <div>
      <p>this is app</p>
      <p>
        {/* click is children */}
        <Button className="button">click me!</Button>
      </p>
      <p>
        <Button className="button">
          <span>this is button</span>
        </Button>
      </p>
    </div>
  )
}

export default App
